Study of interactive free‐energy relationships on ruthenium(III) catalyzed oxidation of phenyl styryl ketone and its substituted analogues by V(V) in acid medium

Kinetics of Ru(III) catalyzed oxidation of phenyl styryl ketone (PSK) and its substituted analogues by V(V) has been investigated in aqueous acetic acid‐sulphuric acid medium in the temperature range 298–313 K. First‐order dependence each on V(V)], PSK], Ru(III)] was observed. Inverse first‐order dependence was observed for V(IV)]. The rate decreased with the increase in dielectric constant (D) of the medium. The rates were enhanced by electron‐donating substituents in both the phenyl rings and decreased by electron‐withdrawing substituents. Linear Hammett's plots were obtained for various substituents in benzaldehyde moiety of PSK for a given substituent in acetophenone moiety and vice versa. The mechanism proposed envisages formation of Ru(IV) from V(V) + Ru(III) reaction followed by the attack on by Ru(IV). Applicability of interactive free‐energy relationship has been tested. The cross‐interaction constants q_x and q_y have been determined at different temperatures and possible interpretations discussed. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 581–588, 2000